1. Field of the Invention
The present invention is an apparatus which relates to an antenna and it's structure; especially, the present invention relates to a dual-band antenna structure encompassing two types of wireless local area network frequency bands.
2. Description of Related Art
Antennas are indispensible components for numerous wireless communication products and also play critical roles in contribution to effective reception of aired electromagnetic waves by the communication products. As wireless communication products, or devices and other consumer electronic products become more diverse, requirements imposed upon antenna design are increasingly more in demand than ever before. Each new profile design of the wireless product may require a new antenna design to provide good reception/emission performance, on the other hand, it also has to satisfy the electromagnetic waves of various wireless communication technologies. In this manner, the wireless product designs are constantly placing pressure upon, and necessarily driving the antenna technology to evolve toward the trends of wide-band and microminiaturization.
Booming development of wireless communication technologies rapidly raise the demands for antennas in the market, and current applications including, at least, mobile phones, notebook computers, Global Positioning Systems (GPS), digital TV's, Multiple Input Multiple Out (MIMO) and the like rely on the antenna for enabling signal emission and reception. The antenna is a required component in the wireless communication appliance for contact with external devices, which is integral in transmission and reception of wireless signals. Since the antenna is located at the foremost front of entire radio frequency system, the signal reception quality therein greatly affects operational performance of the whole wireless communication system. As demands from end users on commodity shape, power-saving and transmission speed and range becomes urgent, and requirements of antenna features in different application fields may also vary, so the antenna design inevitably faces even harsher technical challenges.
A conventional wireless local area network or 802.11a/b/g/n access point antenna is mostly composed of a dual-band access point antenna structure, in particular a Multiple Input Multiple Output (MIMO) antenna system. Such type of antenna system usually comprises a single-band 2.4 GHz or dual-band 2.4 GHz/5 GHz antenna, and since such a dual-band antenna has only one single feed, thus when applied to a dual-band or synchronous dual-band router, a switching circuit or duplex circuit needs to be additionally provided therein so as to effectively separate signals modulated in different frequency bands. With the addition of such a circuit, product costs may undesirably increase, which then may further negatively affect the character of the antenna itself, and as a result causing lowered bandwidth, gain, efficiency, and so forth.
Addressing the issues of inconvenience in use, requirements on installation of additional circuits found in the aforementioned dual-band access point antenna system, the disclosures of prior art U.S. Pat. No. I255588 and prior art U.S. Pat. No. 6,448,932 provide a dual-feed dual-band antenna structure designed with two-feed systems, thereby allowing convenient application in a dual-band or synchronous dual-band product without need for placing any additional circuit system therein, thus further saving product costs and demonstrating the optimal features of the antenna. However, in practice, the antenna structure consisting of the above-said relevant technologies requires a large grounding-area for commonly offering a grounding-area or alternatively the use of a plastic base so as to support the antenna, thus increasing the manufacturing outlay and complexity of the antenna. Additionally, since a grounding-area of large size is necessary, the volume of such type of antenna becomes large thereby preventing it from being widely used in various wireless communication products.
Consequently, with regard to the resolution of defects illustrated hereinbefore, the inventors of the present invention propose a reasonably designed solution for effectively eliminating such defects.